How many rehabbers are fitting Solar PV as standard? A large study of over 22,000 homes conducted by the Berkeley Lab, https://emp.lbl.gov/publications/selling-sun-price-premium-analysis found that purchasers are happy to pay a premium for houses that have solar PV fitted. This premium amounts to approximately $4 per watt. With the average solar installation size now hitting 6kW a rehabber can add $24,000 to the sale price, just for fitting Solar PV and in certain States where there are Solar incentives available, this increase in value could be achieved with an investment of as little as $8K - $9k. From a Rehabbers perspective this is free money. Spend $8k - $9k and sell the house for and extra $24K.

This needs to take into consideration location. In Texas the numbers are very different and do not support solar upgrades. 

Don't forget it has to be your primary residence or no solar rebate for you. And stay away from the solar contracts where any buyers would have to qualify for that contract and it would be added to buyer's DTI ratio Possibly killing the sale.

Ps  the seller being willing to pay the extra doesn’t mean anything of the appraisal isnt willing to assign that value  so you get to eat the difference  

You’re probably better off just giving them the info. 

You also have to see what the wishes are of the local power company. For example, here in Modesto, California, Modesto Irrigation District that provides our electricity will not let anyone else install solar on their house. I don't know what they are afraid of, but no more solar allowed.

Wow i'm here in Modesto and i was not aware of the MID restriction.

Originally posted by @Andrew Faukner :

You also have to see what the wishes are of the local power company. For example, here in Modesto, California, Modesto Irrigation District that provides our electricity will not let anyone else install solar on their house. I don't know what they are afraid of, but no more solar allowed.

 Backfeeds that could kill their linemen when the lines are being worked on if the switchgear isn't properly installed.  Also things like poor power quality etc can impact neighbors who are on the same circuit.